Ultrathin Vein-Like Iridium-Tin Nanowires with Abundant Oxidized Tin as High-Performance Ethanol Oxidation Electrocatalysts

Abstract

Iridium (Ir) holds great promise for ethanol oxidation reaction (EOR), while its practical applications suffer from the limited shape-controlled synthesis due to its low-energy barrier for nucleation. To overcome this limitation, the preparation of a new class of ultrathin vein-like Ir-tin nanowires (IrSn NWs) with abundant oxidized Sn is reported. By tuning the ratio of Ir to Sn, the optimized Ir₆₇ Sn₃₃ /C exhibits the highest mass density of 95.6 mA mg^-1 Ir for EOR at low potential (0.04 V), which is 4.1-fold and 20-fold higher than that of Ir/C and the commercial Pt/C, respectively. It also exhibits the smallest Tafel slope of 153 mV dec^-1 and superior stability after 2 h chronoamperometric measurement. Electrochemical measurements and X-ray photoelectron spectra results confirm that the abundant oxidized Sn promotes a complete oxidization of ethanol into CO₂ at low potential. This work highlights the importance of non-noble metal on enhancing the EOR performance.

Keywords: ethanol oxidation; iridium; oxidized Sn; ultrathin nanowires; vein-like.